There is presently the need for determining the peak power of pulses in a pulse train in the radio-frequency (rf) range. Pulse trains of this frequency and pulse widths are typically used in radar systems, and the more narrow pulse widths are used in, for example, radar proximity fuses.
The new generation of radar proximity fuses uses pulse widths and pulse repetition frequencies that cannot be measured by any known, commercially available power meter. The meters are used both for product evaluation and product maintenance.
Some peak power detector circuits are disclosed in some prior art patents, such as U.S. Pat. Nos. 2,946,013; 3,659,101; 4,038,568; and 4,162,444. However, each of these circuits suffer from a droop problem that occurs as the result of the use of an analog storage in capacitors of the peak level of the input signals. The droop problem occurs between repetitive input peaks and/or between the time the peak value is stored and the time the value on the storage capacitor is read. Further, each of the circuits disclosed in the patents requires a large subsystem that must operate with rise times smaller than the width of the smallest pulse to be measured. This requires a considerable amount of expensive and extremely critical high speed circuitry. Further, the peak detecting subsystems in each of these circuits must operate over the entire dynamic range of the signals being measured resulting in the final measurements being subject to all of the non-linearities. Finally, it appears that none of the disclosed circuits can accommodate pulse widths below ten nanoseconds or pulse repetition frequencies greater than 20 MHz.
Other problems with some of the circuits in the prior art include their inability to accurately accommodate a pulse envelope that has two or more local peaks. For example, if a double humped waveform is applied to the prior art devices, where the second hump is higher than the first, some prior art circuits will only detect the level of the first hump because of switches that cut off the input signal once an initial peak is sensed. Other prior art circuits, such as the one depicted in U.S. Pat. No. 4,038,568 will detect the second hump of a double humped waveform even if the second hump is smaller than the first.